(a) Field of the Invention
This invention relates to a false twist spindle disc used in a textile machine, and more particularly it relates to a false twist spindle friction disc having an annular rotor member having high rigidity, a high resistance to centrifugal force and a high melting point (about 300.degree. C.). It also relates to a method of producing the same.
(b) Description of the Prior Art
In a false twist spindle friction disc used in a textile machine for false twisting, urethane rubber has been frequently employed at the twisting section. As for the construction of the conventional friction discs, the following three types are relatively frequently used.
A first type is of a construction wherein, as shown in FIG. 1a, a core element A of non-elastic material is used and liquid rubber B is poured therearound and allowed to set. A second type is of a construction wherein, as shown in FIG. 1b, a rubber element is machined to form a main body C. A third type is of a construction wherein, as shown in FIG. 1c, a ring E of rubber is press-fitted on or bonded to the outer periphery of a core element D of non-elastic material. However, none of these conventinal constructions can be used where they are subjected to high speed rotation. More specifically, 400,000-600,000 r.p.m. has been considered to be their upper limit. The cause thereof lies in the fact that in the conventinal constructions, the rubber itself is under no or almost no restraint. Therefore, the rubber is in a condition in which it will be subjected directly to a bulging phenomenon due to centrifugal force or a pulsating phenomenon during high speed rotation. This results in scatter in the slippage rate and also causes vibrations, thus impeding high speed rotation. According to the conventional method of producing a rotor by pouring liquid rubber, generally, rubber sets in 20-40 seconds when in contact with air. In the process of setting of rubber, air bubbles are trapped in the rubber as the latter sets, frequently resulting in pinholes resembling pockmarks. Directly, said pockmark-like pinholes becomes an oil reservoir, causing slippage and also forming a cause of vibrations in the spinner rolling surface. Indirectly, they form a remote cause of the production of cracks in the rotor. In addition, various tests have revealed that the cause of decreasing the life of the rubber itself lies in the above point.